1. Field
The disclosed concept relates generally to machinery for container closures and, more particularly to liners and methods for lining container closures such as, for example, can ends, with a sealant material.
2. Background Information
It is known to apply sealant material, commonly referred to as compound, to the underside of container closures to facilitate subsequent sealing attachment (e.g., without limitation, seaming) of the closures to containers such as, for example, beer/beverage and food cans.
FIGS. 1A and 1B, for example, show a container closure 1, commonly referred to as a can lid, shell or can end, for sealing the open end of a can 3 (e.g., without limitation, a beer or beverage can; a food can). During the manufacture of the can end 1, sealant material 5 (e.g., compound) is applied in an annular pattern on the underside 7 of the curl region 9 of the can end 1, as shown in FIG. 1A. As shown in FIG. 1B, after the can 3 has been filled, the can end 1 is seamed onto an upper flange 11 of the can 3. The previously applied sealant material 5 is disposed between the curl region 9 of the end 1 and the upper flange 11 of the can 3 to provide an effective seal therebetween.
FIG. 2 shows an example rotary liner machine 13, which is typically used to apply sealant 5 (FIGS. 1A and 1B) to can ends 1 (shown in phantom line drawing in FIG. 2) in relatively high volume applications. The rotary liner 13 generally includes a base 15 having a chuck assembly 17. As shown in FIG. 2, a pivotal upper turret assembly 18, which is disposed over the chuck assembly 17 and includes an electrical tank assembly 19, a rotary compound tank assembly 20, and a number of peripherally disposed fluid dispensing apparatus 21 (e.g., sealant or compound guns). A lower turret assembly 22 (shown in simplified form in hidden line drawing in FIG. 2) rotates the chucks. A downstacker 23 delivers the can ends 1 to a star wheel (hidden in FIG. 2) which, in turn, cooperates with corresponding chuck members 27 of the chuck assembly 17 to support and rotate the can ends 1 relative to the fluid dispensing apparatus 21.
Specifically, the star wheel (not shown) rotates the can ends 1 onto the chuck members 27, which are raised by cams to receive the can ends 1. The chuck members 27 then begin to rotate the can ends 1, which is commonly referred to as “pre-spin”. Once the can ends 1 reach the desired rotational velocity, the sealant 5 (FIGS. 1A and 1B) is applied (e.g., without limitation, sprayed onto) to the can ends 1 by the fluid dispensing apparatus 21. This is commonly referred to as the “spray time.” After the sealant 5 (FIGS. 1A and 1B) is applied, the can ends 1 continue to be rotated for a relatively brief period of time to smooth out the sealant 5. This is commonly referred to as the “post spin time.” Finally, the cams lower the chuck members 27 and can ends 1, and each can end 1 is removed and discharged from the rotary liner 13 via an unloading guide 29, as shown.
Among other disadvantages of such rotary liner designs, the pivotal turret assemblies (e.g., without limitation, upper turret assembly 18, electrical tank assembly 19, rotary compound tank assembly 20, and lower turret assembly 22 of FIG. 2) are relatively complex and require a number of components that are susceptible to failure such as, for example and without limitation, electrical and compound rotary unions, and associated processors. The centrifugal forces associated with rotation of the spray guns 21 also create a variety of problems. For example and without limitation, air rushing past the nozzles of the rotating guns 21 causes issues with nozzles collecting compound, then throwing compound, requiring surfaces to be cleaned. Furthermore, the fact that all of the sealant guns 21 rotate together means that the entire system must be shut down in order to maintain or clean a single gun 21.
There is, therefore, room for improvement in liner machines and associated methods.